7-Alkoxycarbonyl-4-hydroxymethyl-1-phthalazone compounds

ABSTRACT

WHEREIN R4 is hydrogen or halogen atom, an alkyl, or alkoxy group; R5 is a hydrogen or halogen atom, an alkyl, alkoxy, or alkoxycarbonyl group; R2 is a hydrogen or halogen atom, an alkyl, or alkoxy group; R3 is a hydrogen or halogen atom, an alkyl, alkoxy, alkoxycarbonyl, amino, or acylamino group; with the proviso that at least one of R, R1, R2 and R3 is not hydrogen.   WHEREIN R is a hydrogen atom or an alkyl group; R1 is a hydrogen atom, an alkyl, alkylsulfonyl, or arylsulfonyl group; or an aryl group which is represented by the formula:   1-Phthalazone derivatives or acid salts thereof which are represented by the formula:

United States Patent 1 91 Inoue et al.

145] Feb. 4, 1975 [21] Appl. No.: 275,171

[30] Foreign Application Priority Data 1 Aug. 5, 1971 Japan 46-58643[52] US. Cl. 260/250 P, 260/141, 260/3463, 260/3432 R, 260/471 R,260/473 R, 260/475 R, 260/518 A, 260/519, 424/250 [51] Int. Cl C07d51/06 [58] Field of Search 260/250 P [56] References Cited UNITED STATESPATENTS 3,497,512 2/1970 Hofer et a1 260/250 FOREIGN PATENTS ORAPPLICATIONS 6/1959 France 260/250 OTHER PUBLICATIONS Knott, J. Chem.Soc. 1963, 40210.

Simpson,(ed), Condensed Pyridazine and Pyrazine Rings, Interscience, p.102, New York, 1953; QD 401.559.

Kanahara, et al. C.A. 59:3917g.

Primary ExaminerDonald G. Daus Assistant Examiner-Ralph D. McCloudAttorney, Agent, or Firm-Sherman & Shalloway [57] ABSTRACT l-Phthalazonederivatives or acid salts thereof which are represented by the formula:

\ooH R R wherein R is a hydrogen atom or an alkyl group; R is a hydrogenatom, an alkyl, alkylsulfonyl, or arylsulfonyl group; or an aryl groupwhich is represented by the formula:

wherein R is hydrogen or halogen atom, an alkyl, or alkoxy group; R is ahydrogen or halogen atom, an alkyl, alkoxy, or alkoxycarbonyl group;

R is a hydrogen or halogen atom, an alkyl, or alkoxy group; R is ahydrogen or halogen atom, an alkyl, alkoxy, alkoxycarbonyl, amino, oracylamino group; with the proviso that at least one of R, R R and R isnot hydrogen.

2 Claims, No Drawings l 7-ALKOXYCARBONYL-4-HYDROXYMETHYL-l- PHTHALAZONECOMPOUNDS The present invention relates to new phthalazone derivativesor pharmaceutically acceptable acid salts thereof for pharmaceuticaluse, and to a process for their manufacture.

One aspect ofthe invention consists of l-phthalazone derivatives whichare represented by the formula:

coH

wherein R is a member selected from the group consisting of a hydrogenatom and an alkyl group, preferably a C -C alkyl group; R, is a memberselected from the group consisting of a hydrogen atom, an alkyl group,

preferably a C C; alkyl group, an alkylsulfonyl group,

preferably an alkylsulfonyl group having a C,C,, alkyl group, anarylsulfonyl group, preferably benzenesulfonyl and toluenesulfonylgroups and an aryl group which is represented by the formula:

wherein R, is a member selected from the group consisting of a hydrogenatom, a halogen atom such as Cl, Br, I and F, preferably Cl and Br, analkyl group, preferably a C,C alkyl group, and an alkoxy group,preferably a C -C alkoxy group; R is a member selected from the groupconsisting of a hydrogen atom, a halogen atom such as Cl, Br, I and F,preferably Cl and Br, an alkyl group, preferably a C -C alkyl group, analkoxy group, preferably a C -C alkoxy group, and an alkoxycarbonylgroup, preferably an alkoxycarbonyl group having a C -C alkoxy group;

R is a member selected from the group consisting of a hydrogen atom, ahalogen atom such as Cl, Br, I and F, preferably Cl and Br, an alkylgroup, preferably a C -C alkyl group, and an alkoxy group, preferably aC -C alkoxy group; R is a member selected from the group consisting of ahydrogen atom, a halogen atom such as Cl, Br, I and F, preferably Cl andBr, an alkyl group, preferably a C -C alkyl group, an alkoxy group,preferably a C -C alkoxy group, an alkoxycarbonyl group, preferably analkoxycarbonyl group having a C -C5 alkoxy group, an amino group, and anacylamino group, preferably an acylamino group having a C C acyl groupwith the proviso that at least one of R, R R and R is not a hydrogenatom.

The above'compounds can be manufactured by any of thefollowingprocesses:

a. A compound of-theformula:

wherein R,, R and R have the same meanings as in formula (I) and Y is analkoxycarbonyl group, preferably an alkoxycarbonyl group having a C -Calkoxy group, or a halogenocarbonyl group having a halogen atom such asCl or Br, is reacted with an alkali metal borohydride in the presence orabsence ofa metal halogenide.

b. A compound of the formula:

R P R Xi I L R III V, R, l 0

wherein R, R and R have the same meanings as in formula (l), is reactedwith a hydrazine derivative of the formula:

NH NHR wherein R, has the same meaning as in formula (I), excluding anaryl group.

c. A compound of the formula:

wherein R,, R and R have the same meanings as in formula (I), and Z isan alkoxycarbonyl group, preferably an alkoxycarbonyl group having a C-C alkoxy group, an aldehyde or acyl group, preferably a C -C acylgroup, is reacted with a Grignard compound of the formula,

RMgX

wherein R has the same meaning as in formula (1), excluding a hydrogenatom, and X is a halogen atom such as Cl, Br or I.

The compounds of the present invention can be manufactured by anyprocess described above. These compounds prepared are new. In theex'perimental atherosclerosis induced by cholesterol feeding, theyshowed a profound effect for preventing atherosclerosis, inhib itingcholesterol deposition on arterial wall. They also prevented theenhancement of coagulability and thrombogenicity induced a one shottreatment of an animal with cholesterol or adrenaline. That is to say,they prevented the shortening of clotting times of the blood as well asthe enhancement of adenosine diphosphate-induced platelets-aggregationin the animal. The

compounds of this invention are useful for treatment of atheroscleroticand thrombotic diseases such as cerebral thrombosis, coronarythrombosis, peripheral thrombosis, cerebral atherosclerosis, coronaryatherosclerosis, arteriosclerosis obliterans. thromboangitis obliterans,thrombophlebitis, angiopathy of diabetes mellitus, and nephropathy ofdiabetes mellitus. l tured by the following reaction schemes.

R R R o 2 COCH *1 1) X\/ D ooeH Br i I a 1 r. "a s t 1 a R 7 COOH coon2, 5 R ll (9 (III) R R R 11) 2 C 2 XX o CH7OH 00011 S0612 0001 i z 74/CO -\coocn 5 (JOOLH R2 R 5 0 OOCHN R 2 i 2 (III) The starting compoundsused in this invention, which are expressed by formulae (II) and (Ill),can be manufactured by the analogous methods known in the art or the newmethods described hereinafter.

l. The compounds of formula (ll) can bemanufactured by known methods[e.g., .l. of Am. Chem. Soc., 68, 1316 (1946)] from naphthalenederivatives. Examples of the compounds include 4-ethoxycarbonyl-2-phenyll -phthalazone, 4-methoxycarbonyl-2-methyll phthalazone,4-ethoxycarbonyl-2-methanesulfonyl-lphthalazone,4-methoxycarbonyl-2-benzenesulfonyl-lphthala-zone,4-ethoxycarbonyl-2-toluenesulfonyl-lphthalazone,4-ethoxycarbonyl-2-tolyl-l-phthalazone,4-methoxyc'arbonyl-2-(p-methoxyphenyl l phthalazone,4-ethoxycarbonyl-2-(p-chlorophenyl)-lphthalazone,4-ethoxycarbonyl-2-(p-bromophenyl)-lphthalazone,4-ethoxycarbonyl-2-(p-ethoxycarbonylphenyl)-l-phthalazone, and4-chlorocarbonyl-2-phenyl-l-phthalazone. Furthermore, 4-alkoxycarbonylor4-chlorocarbonyl-l-phthalazone derivatives which have one or twosubstituents such as a chlorine atom, bromine atom, alkyl, alkoxy, aminoacetylamino, alkoxycarbonyl group in any of the C-5, C-6, C-7, and C-8positions in the phthalazone nucleus, can also be used.

The authors of Ber. 40, 72 (1907) and Annual Report of Department ofPharmacy, Kanazawa University (Japan), Vol. 12, 1-6 (196l) claimed thatthey had obtained methylenephthalide or 0-1- hydroxyacetylbenzoic acidby hydrolysis of 0-wbromoacetylbenzoic acid. We have found that theproduct is to be 4-oxo-3,4-dihydroisocoumarin. The compounds of formula(III), which have an alkyl substituent at the 3-position, can bemanufactured by the alkylation of 4-oxo-3,4-dihydroisocoumarin. Examplesof the compounds of formula (III) include 4-oxo-3,4- dihydroisocoumarin,3-methyl-4-oxo-3,4- dihydroisocoumarin, 3,3-dimethyl-4-oxo-3,4-dihydroisocoumarin, and their derivatives which have one or twosubstituents such as a chlorine atom or a bromine atom, an alkyl,alkoxy, amino, acetylamino and alkoxycarbonyl group in any of the C-5,C-o, C7, and C-8 positions in the dihydroisocoumarin nucleus.

ln the embodiment of the process (a), the compound of (ll) is reactedwith an equimolar quantity or an excess, preferably between L5 and 10moles per mole of compound (I), of an alkali metal borohydride such assodium borohydride, potassium borohydride, or lithium borohydride. Thereaction is preferably carried out in the presence of metal halogenide,such as calcium chloride, magnesium bromide, lithium chloride, lithiumbromide, or lithium iodide. Sodium trimethoxyborohydride can also beused. When the compound of (11) is 4-alkoxycarbonyl-l-phthalazonederivative, that is, Y in the formula (11) is an alkoxycarbonyl group,lower aliphatic alcohols such as methanol, ethanol or propanol canpreferably be used as a solvent, and the reaction is preferably carriedout at a temperature between 0 and 150C., especially between 0C. and100C. When the compound of (11) is the 4-chlorocarbonyl-lphthalazonederivative, that is, Y in the formula (11) is a chlorocarbonyl group, asolvent such as dioxane, tetrahydrofuran or benzene can preferably beused, and the reaction is preferably carried out at a temperaturebetween 0 and 100C., especially between 0 and 50C.

In the embodiment of process (b), a compound of formula (11]) is reactedwith an equimolar quantity or excess [preferably 1-10 moles per mole ofthe compound (11111 of a hydrazine derivative represented by formula(IV). Examples of the hydrazine derivative include hydrazine,methylhydrazine, methanesulfonylhydrazine, benzenesulfonylhydrazine, andp-toluenesulfonylhydrazine. Although the reaction can be carried out inthe absence of solvent, it is carried out preferably in the presence ofa solvent such as water, lower aliphatic alcohols, e.g. methanol,ethanol or propanol, and at a temperature between 0 and 150C, especiallybetween 50 and 100C.

In the embodiment of process (c), the reaction can be carried out underthe conditions conventional to Grigard reactions. Namely, the reactionis carried out in an anhydrous solvent such as ethyl ether. benzene ortetrahydrofuran. The reaction temperature between 0 and 100C, especially0 and 50C. is preferably used. The Grignard compound of formula (V) isused in a quantity of l-3 moles per mole of the compound of formula(V1).

Whatever process of manufacture is used, the product can be separatedand purified by conventional methods to be described hereinafter.

The products of the present invention can form stable salts with apharmaceutically acceptable inorganic acid such as sulfuric acid,hydrochloric acid, hydrobromic acid or hydroiodic acid, and an organicacid such as oxalic acid, maleic acid, citric acid, tartaric acid,nicotinic acid, salicylic acid and acetylsalicylic acid. These salts arewater-soluble, and therefore they can be administered in the form ofinjection.

The invention is illustrated but not limited by the following Examples.All the UV spectra described in the Examples were measured in 95 percentethanol.

EXAMPLE 1 To a stirred suspension of 2 g of 7-methoxy-4-ethoxycarbonyl-l-phthalazone 100 ml in methanol, 3 g of sodiumborohydride were added portionwise. The reaction mixture was refluxedfor 1.5 hours on a water bath. The excessive borohydride was destroyedby addition of acetone, and then the solvent was distilled off. Theresidue was dissolved in water, and the solution was adjusted to pH 6-7with acetic acid and dried under reduced pressure. The residue wascontinuously extracted with chloroform using a Soxlet-apparatus. Thechloroform was distilled off from the extract, and the residue soobtained was recrystallized from methanol to yield 1.5 g of4-hydroxymethyl-7-methoxy-lphthalazone melting at 229230C.

Analysis of elements:

UV spectrum: Amax 222 mp. (=20,700), 280 mp. (=9,800), 286 mp. =9,800),302 mp (=4,800). 314 mp. (=5,000) 327 mp. =3,600

EXAMPLE 2 To a solution of 3 g of 4-ethoxycarbonyl-2-phenyl-1-phthalazone 150 ml of methanol, 1.2 g of sodium borohydride and 100 mgof calcium chloride were added portionwise with stirring. The reactionmixture was refluxed for 1.5 hours on a water bath. After cooling,acetone was added to destroy the excessive borohydride, and then thesolvent was distilled off. The residue was dissolved in water, and thesolution was adjusted to pH 6-7. The solution was then extracted withchloroform. The chloroform extract was dried over MgSO4 and distilledoff. The residue was recrystallized from acetone to yield 2.5 g of4-hydroxymethyl-2-phenyl-1- phthalazone melting at 160-162C.

Analysis of elements:

Calcd. 1% 1 for C,.-,H,,O1N,: 71.41 4.140 11.1

Found 1% 71.43 4.70 11. 1

UV spectrum: Amax 220 mp. (=35,200). 256 mp. =6,700), 295 mp (=7,800)

EXAMPLE 3 To a suspension of 2 g of 4,7-diethoxycarbonyl-lphthalazone in120 ml of ethanol heated at 70-80C 1 g of sodium borohydride 100 mg andmagnesium bromide were added portionwise with stirring. After thecompletion of the addition of borohydride, the reaction mixture wasrefluxed for 1.5 hours. The excessive borohydride was destroyed by theaddition of acetone and the solvent was distilled off. The residue wasdissolved in water. The pH of the solution was adjusted to 67 and thesolution was dried under reduced pressure. The residue was extractedcontinuously with chloroform using a Soxlet-apparatus. The chloroformwas distilled off from the extract, and the residue was recrystallizedfrom methanol to yield 1.4 g of 7-ethoxycarbonyl-4-hydroxymethyl-l-phthalazone.

The product has the following structure.

CH OH L H C OOC Analysis of elements:

C H N Calcd. ("/1 l for C.,H.,0.N,; 58.06 4.97 11.29 Found('/z): 511.254.58 11.46

UV spectrum Xmax 215 mp =29,100), 230 mp. (=22,700), 252 mp. (E=l0,600),262 mp. (=l 1,000), 305 mp. (=10,300), 317 mp. (=8,500)

EXAMPLES 4 to 14 In a manner similar to Examples 1-3, the followingproducts of formula (1) were obtained from the compounds of formula (11)in a 60-90 percent yield, as shown in the following Table l.

a 0000 H R2 011 011 R R R 1 Table 1 Product Examm.p. ple (recryst. UVspectrum hmax Nos. RI R, R3 solvent) (molecular extincition 4 CH H Hl47-l48C. 227m (19000) 246mg. (6900) (ethyl mg 7400) 287mg 3400 acetate)302mfl, (6500) 313m (3600) 5 CH H 7-CH,,O 181-182 '223lTII-L (23600)283mg 10700) (ethyl 289mfl. (11300) 314 l (5500 acetate) 325mg. (3500) 6H H 7-C1 213 214C. 2l5m;4 (41200 247mg. I (8300) (methanol) 257ma (7200)280m (7900) 286mg (8300) 3l0mp, (4600 32lmp. 3000) 7 CH H 70 l85lll6C.2l5mu (38900) 219m (39400 (eth l 231mg (17100) 257mg. 5100 acetate) 291m(7700) x H H 7-Br 222-223C. 2l7my. 34000) 220m (35900 (methanol) 255my.(6500) 287mp. (8300) 3l0mfl. (4100) 320fll/L 2400 9 C,,H H 7-CH O206-207C. 223 l (33000 28lm/J. (10200 (ethanol) 320m (4300) 10 H H 5-CH-,CONH 206-207C. 222 l (28000) 255m;/. (9000 (methanol) 270m13 (9000)296mg (l l800) 11 H 7-CH O 8-CH CONH 232-234C. 230mg (14000) 295ml].(4200 (methanol) 328mg (2900) 12 CH H 7-Br 192-193C. 222mu (38600)242mg. (l3800) (methanol) 259mg. (5800) 292m;& (8800) 323mg (2800) 13CH3SOZ H H l76-l77C. 223"][1- (12500 260mg (7800) (ethanol- 290m/J-(9300) 307m# (9700 hexane) 14 -CH ,-C.,H.,S0 H H 160-162C. 222mg (20800)262mg. (7600) (ethanol- 295m (9100) 310m 2 (9500 hexane) EXAMPLE l5EXAMPLE 16-24 To a stirred solution of] g of4-ethoxycarbonyl-2-(pln amanner similar to Example I, 2, 3 and 15, theethoxycarbonylphenyl)-l-phthalazone in ml ofethafollowing products ofthe formula (I') were obtained nol, l g of sodium borohydride was addedportionwise from the compounds of the formula (ll) in a -90 at 60-70C.The reaction mixture was refluxed for l 45 percent yield, as shown inthe following Table ll.

-Q/ R R hour on a water bath, and then the ethanol was distilled Tablell off. The residue was recrystallized from methanol to Exam Productyield 800 mg of 4-hydroxymethyl-Z-(p-ethoxycar- PM R2 R3 R4 pd mp,(recrystr bonylphenyl)-l-phthalazone melting at l47*l53C. from methanol)Analysls of elements: [6 H H H p43 380 nac- 17 H a H H p-CH O 150 152C.is H H 3'0 5'0 204 206C. 19 H 7-CH 0 H p-CH -,O 191 192C. 20 H 7-Cl H-CH, 0 192 194C. C H N 21 H 7-Cl H p-Br 19s 200C. 22 H 7-Br 3'-Cl 5'-Cl211 2l3C. Calcd. ("/11 for C ,.H,..O,N,; 66.6 4.97 8.64 23 H 7-BR H p-Br197 l99C. H 7-CH3O H p-Br 220 224C.

Found ('7: )1 66.15 4.65 8.87 24 EXAMPLE 25 A mixture of 3 g of7-bromo-4-carboxy-2-methyl-lphthalazone and 30 ml of thionyl chloridewas refluxed gently at 7080C. for 50 minutes on a water bath. The

and 3 g of p-toluenesulfonyl hydrazine in 50 ml in ethanol 50 ml. wasrefluxed for 5 hours on a water bath. The ethanol was distilled off, andthe residue was recrystallized from ethanol-n-hexane to yield 4- excessthionyl chloride was then distilled off, and the 5hydroxymethyl'z'(p'toluenesulfonyl)'l'phthalazone residue was dissolvedin 30ml ofdioxane. To the dioxmelting at 1600-16200 ane solution 2 g ofNaBH was added portionwise at Analysis of elementsi -10C. with stirring.The reaction mixture was fur- C H N ther stirred for l hour, and thenthe solvent was dist tilled off. The residue was dissolved in water andthe m lZl. 2%? 2:5; 3:22 solution was extracted with chloroform. Thechloroform was distilled off from the extract, and the residue EXAMPLE30 was recrystallized from methanol-ethyl acetate to yield 12 g of 7bromo 4 hydroxymethy| 2 methy| In a manner similar to Example 26,7-chlor0-8- phthalazone melting at l92--I93C.amino-4-oxo-3,4-dihydroisocoumarin was reacted with hydrazine to yield7-chloro-8-amino-4-hydroxymethyl- EXAMPLE 26 l-phthalazone melting at232 234C. (recryst. from A solution of I g of 3-methyl-4-oxo-3,4-methanol) in a yield of 67 percent. dihydroisocoumarin and3ghydrazinehydrate in 30 ml UV p r AmaX 220 i 255 i of ethanol was refluxed for 3'hours on a water bath. (9. 0 u 296 M The solution was cooled to the roomtem erature, and then the precipitated crystals were filtere d andrecrys- EXAMPLE tallized from methanol to yield 0.8 g of 4-(a-hydroxy- Asolution of a Grignard compound was prepared ethyl)-l-phthalazonemelting at l58l59C. from 1 g of magnesium ribbon 5.86 g and methyliodide Analysis of elements: 5.86 g in I00 ml of absolute ethyl ether bya conven- C H N tional process. To the Grignard reagent described abovea solution of 2.5 g of 4-ethoxycarbonyl-lgs ii {$3 CwHmOzNz: 23352 {1:23phthalazone in 50 ml of tetrahydrofuran was added 30 dropwise at l0l5C.with stirring. The reaction mix- UV Spectrum: max 225 my (Igloo), 245 mture was refluxed for 2 hours, and then a l0 percent (7100), 253 my(8,200). 28| mil (6,400), 300 ml H SO solution was added slowly. Theprecipitated (4,400 )y 312 nm (2,800) crystals were filtered andrecrystallized from ethanol to yield 2.0 g of4-(a-hydroxyisopropyl)-l-phthalazone EXAMPLE 27 melting at 2l22l3C. Thecompound has the follow- A solution of 3 g of 6,7-dimethyl-4-oxo-3,4- gStructuredihydroisocoumarin and 3 g of hydrazine hydrate in 30 CH ml ofethanol was refluxed for 2 hours on a water bath. After cooling, theprecipitated crystals were filtered 40 and recrystallized from methanolto yield 2.6 g of 6,7- dimethyl-4-hydroxymethyl-l-phthalazone melting atI 253-255c. V N H Analysis of elements: l' C H N O Calcd. (71) for C,,H,o N,: 64.69 5.92 13.72 Analysis of elements: Found (7: )1 64.42 5.86l3.90 C H N EXAMPLE 28 alcd1.(Z1.)forC H, O N,: 64.69 5.92 13.72 In amanner similar to Example 26 and 27, 6,7- Dun (z) 1193dimethyl-4-oxo-3,4-dihydroisocoumarin was reacted with methylhydrazineto yield 2,6,7-trimethyl-4- hydroxymethyl-l-phthalazone melting atl52-l53C. EXAMPLE 32 38 (recrystallized from ethyl acetate/petroleumether). 55 In a manner Similar to Example 31, the following products ofthe formula (I) were obtained from the EXAMPLE 29 compounds of formula(ll) in a -95 percent yield, A solution of 3 g of4-oxo-3,4-dihydroisocoumarin as shown in the following Table II].

R R 2 5 R R r -ou I CH MgI f R 5 R R l (II') '(I) Table III TablelV-Continued Exam- Product Com- The enhancement of intensity of LDs picsR, R R R, R5, m.p. pound 1 Nos. recryst. ADP-1nduced plateletaggregation (mg/kg) solvent) 3 X lM "M 32 H H -toluenesulfonyl)-l-84.114171. 82.51110, 3,000

' 23:3? phthalazone 4- 7- 83.5fl.57 8|.0t3.6% 3.500 33 CH CH H tolax-200C. 25, 'f';mi,

h l l 4-hydroxymethyl-2- 34 H methanesulfonyl-l- 711.415.1 71 75.45.90;3000 p phthalazone 35 CH3 CH H 7-Br l9l-l93 C.

(ethanol) 30 CH CH, CH,, H H l7l-l72C.

(benzene) 3'! CH CH CH,-, H 7-Cl loft-164C. |5

(benzene) 3x p-bromo- CH, CH H 7-CH 0 mil-159C. EXAMPLE 40 phenyl(methanol) Effect of the compounds for the prevention of experimentalatherosclerosis EXAMPLE 39 The compounds of the present mventlon showeda The Compounds of the Present lnvenhon f a profound effect for theprevention of atherosclerosis, Preventlve effect for the enhancement ofcoagulability inhibiting cholesterol deposition on arterial walls in theand thrombogenicity by a one shot treatment of an anlexperimental h hl imal ith cho estero of adrenaline, as Shown belOW- 25 Ninetyfive healthymale rabbits were each fed with After oral administrat1on of l0 mg/kg ofthe com- 150 g per day of pellets containing l percent cholespound ofthe present invention to a rabbit, the 1ntens1ty taro] f 15 k Th f 5 bbiabove of platelet aggregation induced by adenosine diphoS- tioned weresacrificed. The remaining 90 rabbits were Phate was measured y theBorn's method (Born, divided into six groups. While all ofthe groupswere fed Physloh 67 See also OBflen, Clln- Pathwith standardized food,the five groups were adminis- 15,452 (1962), Lancet. 1. 7 tered eachwith l0 mg per kg of the compound of the A rabbit was injected thadrenaline #g/ g) 3 present invention, the remaining one group withplahours after oral administration ofthe sample. Five mincebo consistingpotato starch, After 6, IO and 20 Utes aft the nje ml of blood weretake" weeks, and each five rabbits of the six groups were sacfrom thecarotid artery and then diluted with 0.5 ml of rific'ed,'and the totalcontents of cholesterol in the artea 3.8 percent solution of sodiumcitrate. After centrifurial walls were estimated by gas chromatography.The gation ofthe blood at 1000 g. for 30 minutes, 0.9 ml aliresults areshown below in the Table V. quots were taken from the supernatant. Tothe aliquots l. The total-cholesterol content at the end of the first0.1 ml of 3 X 10 molar and i0 molar solutions of 15 weeks was 48.09 i l1.6 ug/mg dry weight. adenosine diphosphate were added. Therefore the 402. The total-cholesterol contents of the six groups molar concentrationsof ADP in the serum were 3 X were indicated in the following table. Thecontents l0 and 10 respectively. The intensity of platelet agwere shownin pg unit per one mg of the dried arterial gregation was measured usinga platelet aggregation wall. The value in the table is the average offive rabmeter (Model 169, Evans Elect. Ltd. England). lntensibits. tiesof the ADP-induced platelet aggregation were shown as percentage of thepre-injection value. As shown in the following Table IV, the compoundsof this Table v invention showed lower values of the ADP-inducedplatelet aggregation, thus preventing enhancement of G d d dcoagulability and thrombogenicity. In the following Tamups a i ere withf t f ble, LDs values of the compounds of the invention are also shown.placebo 8 3 f 20 26.0 1 6.4 Table Iv 4hydroxymethyl-Z-phenyl- 6 29.4 t2.2

l-p thalazone Com- The enhancement of intensity of LD-, 10 i 20 5.3 I3.2 pound ADP-induced Platelet ggregation (mg/kg) gif gg gggg 6 i 1012.4 t 2.1 3x 10 M 10 M d I 20 73:26 saline (control) l2l.8:7.87115.131.9 70 fj$$ 6 289:4" dibenzyline (control) lOl.7i8.7'7c lO6i7i7.3%l0 l4 6 3 5 pyridinolcarbamate l09.0fl.971 100816.59: 20 I (control) 4.d I I aspirin (control) l06.0;* 3.07 111512.671 l gggj'gif fififi 64-hydroxymethyl-2- 79.3t4.37z 77.0i3.37z 4.000 0 3 9 3 8phenyl-l-phthalazone 20 2 4-(a-hydroxyethyU-l 82.0fi.27z 793:3.17: 3.5005 4 hydroxymethyblmethoxw 6 28'7 I 5'] -phthalazone l-phthalazonc 4-(ahydroxylsopropyh- 78.5:287: 769:4.27: 3,500 l0 l3 6 I 3 I l-phthalazone20 1 4-hydroxymethyl-2-(p What is claimed is:

l. A compound of the following formula:

cu on

1. A COMPOUND OF THE FOLLOWING FORMULA: 2.7-Ethoxycarbonyl-4-hydroxymethyl-1-phthalazone or a water-soluble,pharmaceutically acceptable acid salt thereof.